One type of earplug that is used to block intense noise from entering workers' ear canals, includes a body of soft resilient foam material that is of greater diameter than the ear canal and that is inserted into the ear canal. Such insertion can be attempted by the worker placing the front end of the soft foam earplug body against the entrance to his/her ear canal, and then pressing forwardly against the rear end of the foam body. In practice, it is found to be almost impossible to insert the earplug by pressing against its rear end. Since the body front portion has a greater diameter than the ear canal, the earplug meets resistance, and since the body is soft it tends to buckle. One solution is to form the body of slow recovery foam material that can be rolled in the fingers to a small diameter, inserted into the ear canal, and held there until it expands. However, the earplug tends to become dirty if the worker's fingers are dirty.
It is found that insertion of a very soft body such as one formed of soft foam, can be facilitated by the use of a core that is much stiffer than the body and that has a front end lying deep in the body. U.S. Pat. No. 4,434,794 shows a core or stiffener that can be slid into a shell-shaped body to help its insertion. U.S. Pat. Nos. 5,573,015 and 6,659,103 show a stiffener lying within and bonded to a foam body and manufactured by extrusion. One problem encountered in the use of a stiffener or core such as the type shown in U.S. Pat. No. 5,573,015, is that there is a possibility that the front end of the core will rub against the ear canal during earplug insertion, especially if the person's ear canal is highly curved. Even if such rubbing is unlikely, people who are required to wear the earplug may be concerned about the possibility of such rubbing, especially if they press a finger against the front end of the earplug and notice the stiff core at the front end. An earplug with a stiffener, that avoided the possibility of the stiffener front end scraping against the wearer's ear during insertion, and that could be mass produced at low cost, would be of value.